"Ed Sirett" wrote in message
news
On Fri, 02 Apr 2004 00:47:41 +0100, John Rumm wrote:

Dave Plowman wrote:

'Zone valves, etc' require a basic understanding of electricity to
install. Guess why our resident 'expert' doesn't like them...

It is interesting to watch in a way, but he seems to live in a world
totally governed by "rules of thumb".

If you mean me, I am a maths man. I give pointers here.

Don`t understand heat loss calcs? apply rule "you need 400mm of
insulation and tin foil under your tiles".

I think you are probably onto to something. This might account in a
bizarre way why many of us find ourselves exhorted to do things a certain
way (regardless of economics, customer expectations, practicalities, the
laws of physics, ...), whilst we are told that design calculations should
be left to 'experts'.

Most installers do rule of thumb installations. The only thing they may
calculate is the rad sizes from a scale rule. A one size fits all boiler
they buy, so no need to do that either. Balance it? Fully open downstairs
and half open upstairs and put TRVs all around to get them out of jail.
Most do things a certain way because that is the only way they know. Or "we
always do it this way", which is typically British. Hence foreigners laugh
at our outdated poor performing plumbing and heating systems.

Very little innovation in heating and water systems came from Britain. I
can only think of the thermal store (in the modern sense) in 1985 and the
unvented cylinder in 1863, which Britain only adopted in 1986. Condensing
boilers, combi's, system boilers, instant water heaters, alloy tubed heat
exchangers? Nope. All Continental.